1. Field of the Disclosure
Four independent technologies are incorporated in this invention to efficiently and cost effectively implement dynamic last mile connectivity. The four technologies are passive optical networks (PON), Small cell, wavefront multiplexing (or K-muxing), and digital beam forming (DBF). We have filed US patents for communications architectures featuring K-muxing overlaid over low cost of PON. Those inventions relate particularly to resource allocation in passive optical networks (PON) via wavefront multiplexing (WF-muxing or K-muxing) and wavefront demultiplexing (WF-demuxing or K-demuxing). The “WF-muxing in PON” can be configured for performing remote digital beam forming (RDBF) over a service area covered by multiple small cells. The RDBF may generate multiple shaped beams with enhanced connectivity and better isolations over a same frequency slot concurrently to serve multiple users over the coverage area.
2. Brief Description of the Related Art
Wavefront multiplexing/demultiplexing (WF muxing/demuxing) process embodies an architecture that utilizes multi-dimensional waveforms in various applications. Multiple data sets are preprocessed by WF muxing before stored/transported. WF muxed data is aggregated data from multiple data sets that have been “customized/processed” and disassembled into any scalable number of sets of processed data, with each set being stored on a storage site or being transported via a propagation channel. The original data is reassembled via WF demuxing after retrieving a lesser but scalable number of WF muxed data sets. The WF muxing/demuxing solution enhances data security and data redundancy in some applications, and facilitates dynamic resource (power and bandwidth, etc.) in others. In addition, WF muxing/demuxing methods enable a monitoring capability on the integrity of stored/transported waveforms.
K-space is a well understood term in solid state physics and imaging processing. The k-space can refer to:                a. Another name for the frequency domain but referring to a spatial rather than temporal frequency        b. Reciprocal space for the Fourier transform of a spatial function        c. Momentum space for the vector space of possible values of momentum for a particle        d. According to Wikipedia (September 2015), the k-space in magnetic resonance imaging (MRI)                    i. a formalism of k-space widely used in magnetic resonance imaging (MRI) introduced in 1979 by Likes and in 1983 by Ljunggren and Twieg.            ii. In MRI physics, k-space is the 2D or 3D Fourier transform of the MR image measured.                        
We shall introduce the terms K-mux, Kmux, or KMx for representing the Wavefront multiplex; and K-muxing, Kmuxing, or KMxing for the Wavefront multiplexing. We may also use “K-Muxing in PON” for “WF-Muxing in PON”, “K-muxer” for “WF muxer”, and so on. In Electromagnetic (EM) theory, the letter K is often used to represent a directional vector and is a wave number in a propagation direction. The term (ωt−K·R) has been used extensively for propagation phase. K represents a directional (moving) surface and R a directional propagation displacement. Both are vectors. Therefore a vector K is a “wavefront” mathematically. We will be using k-space as wavefront domain or wavefront space.
The present invention relates to methods and architectures for dynamic allocations of time slots or equivalent bandwidths of Passive Optical Networks (PON) via wavefront multiplexing (WF muxing or K-muxing) and wavefront de-multiplexing (WF-demuxing or K-demuxing) techniques to generate multi-dimensional waveforms propagating through existing time slots of PON network concurrently, enabling usage exceeding the bandwidth limits set by time slots or subchannels bandwidths for a subscriber. The architectures support dynamic bandwidth allocations as well as configurable bandwidth allocations. They also support dynamic “power resources” allocations as well as configurable power resources allocations of optical lasers to different signals of various subscribers.
It is also related to Digital beam forming (DBF) over a region for subscriber operation. Wireless network via the DBF shall optimize connectivity and minimize interference among multiple concurrent users. It may form a shaped beam, or multiple dynamic beams with orthogonal beam (OB) patterns. DBF can be implemented locally within the perimeter of a subscriber. It may also be implemented remotely via a remote beam forming (RBF) technique. DBF is a digital technique for implementing a beam-forming network (BFN). Similarly a remote beam-forming network (RBFN) may also be implemented digitally via remote DBF techniques.
Cellphone industry has responded to the increasing data transmission demands from smartphones, tablets, and similar devices by the introduction of 3G and 4G cellular networks. As demand continues to increase, it becomes increasingly difficult to satisfy this requirement, particularly in densely populated areas and remote rural areas. An essential component of the 4G strategy for satisfying demand is the use of picocells and femtocells. Together, these are classified as small cells. The term small cell is an umbrella term for low-powered radio access nodes that operate in licensed and unlicensed spectrum that have a range of 10 m to several hundred meters. Small cells now outnumber macro-cells and microcells combined, and the proportion of small cells in 4G networks is expected to rise.
A small cell is defined by a low-power, short range, self-contained base station. Initially used to describe consumer units intended for residential homes, the term has expanded to encompass higher capacity units for enterprise, rural and metropolitan areas. Key attributes include IP backhaul, self-optimization, low power consumption, and ease of deployment.
The small cell access point is a small base station, much like a Wi-Fi hot spot base station, placed in a residential, business, or public setting. It operates in the same frequency band and with the same protocols as an ordinary cellular network base station. Thus, a 4G smartphone or tablet can connect wirelessly with a 4G small cell with no change. The small cell connects to the Internet, typically over a DSL, fiber, or cable landline. Packetized traffic to and from the small cell connects to the cellular operator's core packet network via a small cell gateway.
There are several differences between picocells and femtocells. Typically, picocells cover a larger area than a femtocell and are installed and operated by the carrier. A femtocell on the other hand, is designed to be installed by the network customer. An example of the use of the femtocell is to provide coverage in the home or in a small office setting. Typically, a femtocell can serve only somewhere between 4 and 16 simultaneous users, whereas a picocell may be able to handle up to 100 users.
Small cells have been proposed as solutions for 5G, allowing frequency reuse efficiently but also moving the network complexity from base-stations to backbone network controls. PON can be used as the backhaul of small cell deployments.
According to the paper “Cost Optimization of Fiber Deployment for Small-cell Backhaul” by C. S. Ranaweera; et al. on Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC), 2013, many optimized PON deployments for various scenarios have been studied. However, cost-efficient deployments of PONs for small cell backhauling using existing infrastructure adds complexity because the existing resources must be taken into account. It has been shown in the paper, cost-efficient PON deployments using existing fiber resources for the purpose of small cell backhauling by determining the fiber routes, the best locations for splitters, and the most favorable number of PONs for a range of split ratios. For a test case, the resulting cost-optimized PON can save up to 56% of the deployment cost associated with small cell backhauling, in comparison to typical Ethernet based PTP fiber backhauling approaches.
In addition, DBF over multiple small cells via a remote digital beam forming (RDBN) network at a head-end of a PON will make frequency reuse more efficient than conventional optimizations of small cell radiations.
Remote beam forming (RBF) has been implemented in all TDRSS satellites in 1980s using FDM muxing among back-channels in feeder-links. Their RBF were implemented by analogue means. Remote digital beam forming (RDBF) was used in many mobile satellite systems (MSS) in early 2000s via techniques of ground base beam-forming (GBBF) using FDM muxing among back-channels in feeder-links. Most of the concerns and difficulties in implementation of RBF or RDBF are related to dynamic calibrations, and equalization of multiple channels in a feederlink, maintaining coherent operation among multiple array elements on board satellites.
A US patent with the U.S. Pat. No. 5,903,549 by Von der Embse et al in 1999 proposed a CDM muxing scheme in feeder links for mobile satellite applications. Since CDM muxing covering entire bandwidth of feeder-links, variations on amplitude and phase delays over multiple CDM channels are minimum. Thus dynamic calibration and equalizations among propagation channels in feederlink become less an issue.
In this patent application we are proposing a K-muxing scheme, over a TDM in PON format, with capability for continuous and dynamic calibration and equalization among multiple backchannels in feeder-links for terrestrial wireless communication applications. The feeder-links for the PONs are the time slots via fibers. Thus dynamic calibration and equalizations among propagation channels in feederlink may become an issue. Similar K-muxing scheme can be overlaid over FDM or CDM channels for many wireless communications applications; including those via satellites and via terrestrial hubs. They also are applicable to cable networks.
3. Background in PON.
Most of the Fiber-to-the-Home deployments in recent years have been based on industry standard technologies such as Gigabit Ethernet Passive Optical Networks (GEPON) and Gigabit PON (GPON). Passive Optical Network (PON) is a point-to multipoint network. A PON consists of optical line terminal at the service provider's central office and many number of optical network units near end users. The goal of PON is to reduce the amount of fiber. There are two standards of the Passive Optical Network available, the GPON and the GEPON. GPON (Gigabit PON) is the evolution of broadband PON (BPON) standard. The protocols used by GPON are ATM, GEM, and Ethernet. It supports higher rates and has more security.
GEPON or EPON (Ethernet PON) is an IEEE standard that uses Ethernet for sending data packets. By 2010, there were over 15 million EPON ports installed. GEPON uses 1 gigabit per second upstream and downstream rates. EPON/GEPON is a fast Ethernet over passive optical networks which are point to multipoint to the premises (FTTP) or fiber to the home (FTTH) architecture in which single optical fiber is used to serve multiple premises or users.
The success of these deployments has led to significant innovation in both system architecture and the components that are used to build these systems, and the next generation of passive optical networks will inevitably be far more advanced than what is typically deployed today.
Traditional PON architectures feature one optical feed shared among 32 or more users, as depicted in FIG. 1. In a GPON or GEPON system all subscribers use a common optical wavelength. They share the fiber infrastructure, which is done through time division multiplexing (TDM). Each of those 32 homes transmits over the same fiber, but the time in which they are allowed to “occupy” the fiber is allocated by the Optical Line Terminal (OLT) at the central office. While the equipment in each home is capable of transmitting at over 1,250 Mbps, it can only do so during its allotted time on the fiber, and therefore it is not uncommon for each subscriber in a legacy PON system to only achieve sustained data rates of around 30 Mbps. This concept of many users sharing a common fiber helps minimize the fiber infrastructure required in an FTTH deployment.
An Optical Line Terminal (OLT) provides a direct optical interface to the Ethernet/IP network core. Together with Optical Network Unit (ONU), it completes the end-to-end optical last mile with up to 1 Gbps of bandwidth to residential and business customers.
An OLT may consist of 4 PON cards, each card with 2 PON links, total up to 8 PON links. Each PON link delivers 1 Gbps of shared bandwidth between up to 32 subscribers within 20 Km reach. An OLT may serve a maximum of 256 subscribers from a 19″ 2RU chassis. With layer 2 switching capability, OLT has up to 8 optical or electrical gigabit uplink ports.
According to Wikipedia, there are also many variations in PONs such as:
1. TDM-PON                APON/BPON, EPON and GPON have been widely deployed. By 2015, EPON has approximately 40 million deployed ports and ranks first in deployments. GPON growth has been steady, but fewer than 2 million installed ports.        For TDM-PON, a passive optical splitter is used in the optical distribution network. In the upstream direction, each ONU (optical network units) or ONT (optical network terminal) burst transmits for an assigned time-slot (multiplexed in the time domain). In the downstream direction, the OLT (usually) continuously transmits (or may burst transmit).        
2. DOCSIS Provisioning of EPON or DPoE                Data over Cable Service Interface Specification (DOCSIS) Provisioning of Ethernet Passive Optical Network, or DPoE, is a set of Cable Television Laboratory specifications that implement the DOCSIS service layer interface on existing Ethernet PON (EPON, GEPON or 10G-EPON) Media Access Control (MAC) and Physical layer (PHY) standards.        It makes the EPON OLT look and act like a DOCSIS Cable Modem Termination Systems (CMTS) platform (which is called a DPoE System in DPoE terminology).        
3. Radio frequency over glass                Radio frequency over glass (RFoG) is a type of passive optical network that transports RF signals that were formerly transported over copper (principally over a hybrid fibre-coaxial cable) over PON.        RFoG offers backwards compatibility with existing RF modulation technology, but offers no additional bandwidth for RF based services.        Although not yet completed, the RFoG standard is actually a collection of standardized options which are not compatible with each other (they cannot be mixed on the same PON). Some of the standards may interoperate with other PONs, others may not.        
4. WDM-PON                Wavelength Division Multiplexing PON, or WDM-PON, is a non-standard type of passive optical networking, being developed by some companies.        The multiple wavelengths of a WDM-PON can be used to separate Optical Network Units (ONUs) into several virtual PONs co-existing on the same physical infrastructure.        There is no common standard for WDM-PON nor any unanimously agreed upon definition of the term.        
5. Long-Reach Optical Access Networks                The concept of the Long-Reach Optical Access Network (LROAN) is to replace the optical/electrical/optical conversion that takes place at the local exchange with a continuous optical path that extends from the customer to the core of the network.        
In this application, we will present examples using TDM PON for implementing incoherent K-muxing on information digital data sets, and RFoG for examples using coherent K-muxing on waveform or signal digital data set. In transmit, an information digital data set is converted into a waveform or signal digital data set through modulators. Similarly, a set of received waveform or signal digital data may also be converted to a set of received information data via demodulators.
In short, K-muxing for incoherent operation in data transport and storage are for enhancing data privacy via a superposition formatting on data and improved survivability via data redundancy. On the other hand, K-muxing for coherent operation in signal transmission via multiple channels are for coherent power combining to achieve enhanced signal-to-noise ratio (SNR) in a receiver, and dynamical resource allocations for communications applications. The resources include both power and bandwidth.